Storing renewable energy as ammonia

Posted by Roy van IJzendoorn

It’s currently impossible to store large quantities of energy produced by wind and solar power. In the Netherlands in times of over-supply the energy is sold off cheaply; in times of need gas-powered plants must make up the deficit.

Materials challenges

Ammonia – Condensed ammonia is a corrodent, and in anhydrous state it can cause stress-corrosion cracking of stressed carbon steels or high-strength, low-alloy steels.

Hydrogen – it itself it is not corrosive but it can lead to blistering and embrittlement of steel. Also, it readily combines with other elements to product corrosive compounds.

Thanks to the growing number of wind turbines and solar panels, the supply of renewable electricity will sharply increase in the coming years. At times when there is a surplus of renewable electricity, it can be converted to ammonia locally using small-scale plants. Just like natural gas, the produced and stored ammonia can be used by energy companies at any time as fuel for electricity generation. Ammonia can be stored as a liquid; a standard tank of 60,000 m3 contains about 211 GWh of energy, equivalent to the annual production of roughly 30 wind turbines on land. Ammonia can be burned cleanly: water and nitrogen are released, but no CO² and little or no nitrogen oxides.

Recycling the wind

Alexander van Ofwegen, Director of Nuon Heat, elaborates: “This idea consists of three steps. The first step is to convert the electricity garnered from wind power into liquid ammonia. This involves a chemical process wherein hydrogen and nitrogen are bound together to create ammonia. Ammonia is then stored in large tanks for as long as is needed. In this way there will always be a sizeable fuel supply available to be used in times of low energy supply from sustainable energy sources. This is possible due to the fact that ammonia can be used as a fuel that produces no CO²“.

Power to Ammonia

The research of Nuon and TU Delft is a part of the project ‘Power to Ammonia’, wherein the Institute for Sustainable Process

Technology (ISPT) has brought together many different parties to perform research and share knowledge.

Magnum-plant takes the lead

The Nuon Magnum-plant in Eemshaven, the Netherlands, was officially opened in 2013. The original concept revolved around setting up a power plant that would be able to run on different kinds of fuel, like biomass, gas and coal. In consultation with environmental organizations it was decided in 2011 that the Magnum-plant would remain a gasfired power plant until 2020

Research TU Delft and Nuon

Although TU Delft and Nuon are still sitting at the drawing board and a lot of additional research is needed, both parties agree that storing energy in ammonia is a promising technique that after the necessary research and with additional funding

can be made applicable on a large scale in about ten years. Of course both safety and environmental considerations are a major priority during this research.